Whirlpool-type baths have long been the mainstay of athletic training rooms and physical therapy facilities. These baths are used to treat discomfort resulting from strained muscles, joint ailments and the like. The agitating motion of the warm bath water relieves the soreness and promotes tissue regeneration by increasing the flow of blood to the area of the injury. More recently, whirlpools have been found in increasing numbers in health spas and homes as they have gained in popularity as a means of relaxing from the daily stresses of modern life. The bubbling water and swirling jet streams create an invigorating motion that massages the user's body.
To create the desired whirlpool motion and hydromassage effect, jet fittings are typically employed to inject water into the receptacle at a high velocity. In the past, it has been proposed to enhance the whirlpool motion by adapting the fitting to increase the circulation of the water within the receptacle. Henkin et al. U.S. Pat. No. 4,689,839 discloses such a fitting where water is drawn from the receptacle and mixed with the inlet stream in a mixing chamber located externally of the receptacle and remote from the fitting itself. A major drawback of the fitting disclosed in the Henkin patent involves the extra plumbing required to convey water to and from the mixing chamber.
Henk U.S. Pat. No. 4,501,659 discloses a skimmer apparatus for a conventional swimming pool which enhances the skimming operation by increasing the flow therethrough. The apparatus operates solely within the pool. Flow is increased by using the output from a pool filter as an ejector. More particularly, filtered water is directed into a venturi, which entrains the surrounding pool water and discharges the resulting combined stream into the pool. Although the skimmer apparatus of the Henk patent effectively enhances the flow of pool water, its utility is limited to the performance of a skimming operation.
Henkin et al. U.S. Pat. No. 4,731,887 discloses a hydrotherapy jet assembly which is suitable for mounting in a wall of a spa, bathtub or the like. The jet assembly includes a mixing chamber which is supplied with water under pressure by a water jet nozzle. A passageway extends internally through the assembly between the mixing chamber and the spa or tub so that water can be drawn from the spa or tub for entrainment by the water jet. Thus, the stream discharged from the jet assembly into the spa or tub includes the following components: (i) water supplied under pressure into the mixing chamber by the water jet nozzle; and (ii) water drawn or aspirated from the spa or tub for entrainment by the water jet.
The jet assembly disclosed in the Henkin et al. '887 patent can be adapted to draw or aspirate air, as well as spa or tub water, into the mixing chamber. However, in such an adaptation, it is difficult to strike a suitable balance between the amount of aspirated spa or tub water, on the one hand, and the amount of aspirated air, on the other hand, due to the fact that an increase in the quantity of aspirated spa or tub water results in a decrease in the quantity of aspirated air and vice versa. Thus, in order to ensure that the jet nozzle can create a water flow having a velocity which is high enough to entrain both air and spa or tub water, the jet assembly of the Henkin et al. '887 patent is limited to relatively low flow rate requirements and to relatively small nozzles. A delicate balance therefore exists between the size of the passageway for the entrained spa or tub water and the flow rate, which is a function of the size of the jet nozzle, required to make the assembly functional. If built in a larger size for use with a standard size pump typically employed in the hydrotherapy industry, the jet assembly disclosed in he Henkin et al. '887 patent would not work properly, if at all.